Sonic Corp. (Nasdaq: SONC) volatility is higher on the session Thursday following a notable upgrade by Bank of America earlier. The firm boosted Sonic from Underperform to Buy, a rare two-notch call. BofA raised its price target 47 percent to $11 as well.

Option implied volatility is up 11.5 percent from Wednesday's close and 123 percent over its trailing historical average.

Shares are up 5.9 percent on the session.

Of note, shares got above the key $8.50 price level, which had been a previous support level on the shares last August and September, moving to a resistance point in February and March.